This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
As will be appreciated, oil and natural gas have a profound effect on modern economies and societies. Indeed, devices and systems that depend on oil and natural gas are ubiquitous. For instance, oil and natural gas are used for fuel in a wide variety of vehicles, such as cars, airplanes, boats, and the like. Further, oil and natural gas are frequently used to heat homes during winter, to generate electricity, and to manufacture an astonishing array of everyday products.
In order to meet the demand for such natural resources, companies often invest significant amounts of time and money in searching for and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once a desired resource is discovered below the surface of the earth, drilling and production systems are often employed to access and extract the resource. These systems may be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead system through which the resource is extracted. These wellhead systems may include a wide variety of components, such as a high pressure wellhead housing and various casings, hangers, valves, fluid conduits, and the like, that control drilling and/or extraction operations.
As such, when drilling a well for oil or gas, typically a high pressure wellhead housing will be mounted at the outer end of the well that may be used to support one or more tubular strings extending into the well. In one example, a string of casing may be run into and installed within the well. A casing hanger is then located at the outer end of the string of casing, in which the casing hanger lands upon a load shoulder in the high pressure wellhead housing. The load shoulder can be machined into the bore of the high pressure wellhead housing. Alternatively, the load shoulder can be a separate high strength ring that is installed into a groove in the high pressure wellhead housing, such as when the high pressure wellhead housing is initially manufactured. In both cases, the inner diameter of the bore of the high pressure wellhead housing decreases in a downward direction, with the smaller inner diameter located below the load shoulder.
The stepped diameter bore has a disadvantage. Drilling tools can be no larger than the minimum inner diameter located below the load shoulder. However, it is often desired to utilize a drill bit or tool that is larger than minimum inner diameter. For example, in a wellhead system that is used in containment of offshore shallow flow zones, it is desired to run a casing, which is typically has an 18 inch (0.456 m) diameter, through a subsea high pressure housing having a minimum bore that is typically 18.63 inches (0.473 m). The nominal seat of the high pressure wellhead housing (e.g., the insert load shoulder) must be removed or left off of the assembly prior to running a high pressure wellhead housing and then reinstalled subsequent to the installation of the casing. Accordingly, there is a demand to simplify the process of running tools into or through a high pressure wellhead housing that includes a load shoulder.